A driving circuit for protecting a driven switching device, e.g., a MOSFET switch, and the switching device can be integrated into a single protected MOSFET device. Such protected MOSFET devices generally comprise a control-chip as a driver for providing the driving and protection functionality. Moreover, the protected MOSFET devices typically comprise a base-chip in a correspondingly low ohmic power semiconductor technology for implementing the actual MOSFET switching device. To provide the protection functionality, conventionally a temperature sensor element and a current sensor element are integrated into the base-chip to directly sense reliability relevant device parameters like the base-chip device temperature or device parameters from which other reliability relevant devices parameters (e.g., the power dissipated in the base-chip) may be calculated such as the drain current of the MOSFET switching device.
In this context, the directly sensed reliability relevant parameters or device parameters represent feedback parameters from the base-chip to the control-chip such that the control-chip may adapt the driving signal to protect the base-chip. In the example of a MOSFET switching device as base-chip, the control-chip may generate a gate source voltage as the driving signal for the MOSFET switching device within the base-chip which ensures a safe operation of the base-chip.
To provide the above-mentioned different functionalities, the control-chip as driver and the base-chip as driven device are often fabricated in different types of semiconductor technologies and then assembled into a single device package.
Moreover, according to other conventional solutions, the circuits of the control-chip and base-chip may also be monolithically integrated on a single semiconductor substrate using a so-called smart power semiconductor technology. In this way, for instance, the driving and protection circuit providing the signal conditioning functionality and, e.g., an N-substrate vertical Double-diffused Metal-oxide Semiconductor Field Effect Transistor (DMOSFET) providing the power switching functionality may be integrated on the same chip.
The integration into a single package or even onto the same semiconductor substrate provides advantages in terms of a lower complexity of the system comprising the control-chip and the base-chip functionality on an application level. However, these conventional approaches all bear disadvantages in terms of increased costs or reduced reliability.
For instance, approaches to integrate the control-chip as driver and the base-chip as driven device into a single package result in a complex chip assembly. An example for such a complex chip assembly may be seen in FIG. 1 using the so-called chip by chip technology. The chip by chip or the chip on chip technology, which may be used alternatively, not only lead to a complex chip assembly but also to reliability issues. For instance, reliability problems may arise because of the critical chip to chip interconnections, in the example of FIG. 1 the chip to chip bond wires, or due to thermal issues or mechanical stress.
Furthermore, the complex chip assemblies lead to higher packaging costs since special glues, special lead-frames and/or special wafer-back processing may be required to implement the chip assemblies.
Moreover, a further disadvantage results from the fact that the semiconductor technology which is conventionally used for the driven device, here the base-chip, may not be the cheapest and/or the most suitable one. The reason for this is that temperature and current sense structures have to be implemented within this device for providing the above-mentioned feedback signal to the driver, here the control-chip, for protection reasons.
Furthermore, if several devices, in the example MOSFET devices, are to be driven, a redundancy results in the drivers, here the control-chips, since 50% of the area of the control-chips are normally used for so called central functions that could be shared when driving a plurality of MOSFET devices.
A conventional approach for monolithically integrating the above-mentioned functionalities of the control-chip (driver) and the base-chip (driven device) may suffer from high wafer costs. One reason for this may be the additional mask-steps for the temperature and current sense structures which need to be implemented in the base-chip part of the monolithically integrated device.
For these or other reasons, there is a need for the present invention.